Rachel de Boer finally told some friends a secret she’d kept for years: she slept with stuffed socks sewn between the cups of an old bra to prevent cleavage wrinkles and smooth out her neckline.

Three years later, a professionally designed and manufactured version of that same contraption is sold in 150 lingerie shops across the Netherlands and Belgium, approved by a research institute and getting interest from retail outlets in Germany, Austria, Portugal, Spain, Britain and France.

“It started out as my secret, I didn’t want to talk about my wrinkles or the (first) bra I made, which was ugly,” de Boer told Reuters on Thursday. “But I slept like that for seven years and then I turned 40, told my friends and they admitted they also had this problem.”

Skeptical but curious, her friends also wanted sock bras to smooth out their cleavage wrinkles. So De Boer made five more versions of what is now called “La Decollette.”

Her friends were so enthusiastic about the results, they encouraged the former real estate agent to stop selling houses and design an anti-wrinkle night bra that women would want to wear to bed.

La Decollette, which has a soft, padded rectangular piece of material between the collar bone and the sternum and sits between the breasts, was born and to De Boer’s amazement, has addressed a problem many women all over Europe seem to share.

The cupless bra is worn at night and keeps the breasts “in place” to prevent the compressing of breasts together which De Boer says can create vertical wrinkles.

“If you sleep on your back, then you will never have this problem,” she says adding, “Le Decollette works because the breast are separated through the night.”

De Boer’s anti-wrinkle bra has been a hit at lingerie shows around Europe and she said it also has the stamp of approval from the Parisian research institute CERCO or Centre d’Etudes et de Recherches Cosmetologique.

CERCO carried out research on women between 35 and 60 years old and declared that those who wear the bra can see cleavage wrinkles reduced significantly after 24 hours, she said.

De Boer sold 12,000 of the $72 one-size fits all, anti-wrinkle bras last year, expects to sell 25,000 this year and 50,000 next year.

Talks are also underway to ship the bras to the United States and Canada.